Proteomic and toxicological characterization of the venoms of the most enigmatic group of rattlesnakes: The long-tailed rattlesnakes

Among different groups of snakes, long-tailed rattlesnake group is among the least studied ones. This group includes three species namely Crotalus ericsmithi, Crotalus lannomi and Crotalus stejnegeri. The scarcity of studies of these snakes is mainly due to social conditions nearby their area of distribution. However, the identification of their venom can be helpful for evolutionary studies as well as finding proper antivenoms in case needed.

Isolation and identification of peptides and proteins from these snake venoms showed that these venoms contain a marked pre-dominance of Snake Venom Metalloproteinases (SVMPs), followed by phospholipases A2 (PLA2s). Based on the phylogenetically relation of these snakes to ‘viridis’ group which are crotoxin-positive species, it was expect to find crotoxin, but the findings showed otherwise. It means that these venoms are not neurotoxic, but they exhibit high lethal potencies. It was also shown that two commercially available antivenoms in Mexico can neutralise the lethality of three venoms, which can be used in case of biting by these snakes.

How was PEAKS used?

Results obtained from MS/MS were processed with PEAKS to find peptides and assign them to protein families. The UniProt/SwissProt database (Serpentes) was used for database search. Carbamidomethylation of cystein was set as a fixed modification, while deamidation of asparagine or glutamine, and methionine oxidation were set as variable modifications. Maximum missed cleavages by trypsin was set as 2. For filtering the results, FDR was set as 1% with a minimum protein score of 30 and at least 1 unique peptide.

Neri-Castro, Edgar, et al. “Proteomic and toxicological characterization of the venoms of the most enigmatic group of rattlesnakes: The long-tailed rattlesnakes.” Biochimie 202 (2022): 226-236.


The most enigmatic group of rattlesnakes is the long-tailed rattlesnake group, consisting of three species: Crotalus ericsmithiCrotalus lannomi and Crotalus stejnegeri. These species have been the least studied rattlesnakes in all aspects, and no study on the characterization of their venoms has been carried out to date. Our main objective was to investigate the proteomic composition, as well as some of the biochemical and toxic activities of these venoms, and their neutralization by commercial antivenom. The venom proteome of C. ericsmithi mainly contains metalloproteinases (SVMP; 49.3%), phospholipases A2 (PLA2; 26.2%), disintegrins (Dis; 12.6%), and snake venom serine proteases (SVSP; 6.8%), while C. lannomi venom mainly consists of SVMP (47.1%), PLA2 (19.3%), Dis (18.9%), SVSP (6%) and l-amino acid oxidase (LAAO; 2.6%). For these venoms high lethality was recorded in mice, the most potent being that of C. lannomi (LD50 of 0.99 μg/g body weight), followed by C. ericsmithi (1.30 μg/g) and finally C. stejnegeri (1.79 μg/g). The antivenoms Antivipmyn® from SILANES and Fabotherapic polyvalent antiviperin® from BIRMEX neutralized the lethal activity of the three venoms. Although this group of snakes is phylogenetically related to the C. viridis group, no neurotoxic components (crotoxin or crotoxin-like proteins) common in rattlesnakes were found in their venoms. This study expands current knowledge on the venoms of understudied snake species of the Mexican herpetofauna.